A vacuum die-casting machine, which is improved based on a traditional die-casting machine, is generally sealed by adopting a dynamic-sealed connection between an injection rod and a guiding seal assembly; and the dynamic-sealed connection is configured as a radial seal. When a displacement data is required to be collected, a location of a hammer header is generally determined when a contacting ring disposed on the injection rod touches a switch, that is the displacement date is collected by a fixed point measurement. Therefore, the real-time location of the hammer cannot be obtained. In addition, a sealing effect of this structure is often unsatisfied. Especially when the injection rod repeatedly moves backward and forward, a vacuum seal of an injection system often cannot be guaranteed, which may bring great damage to the stability of performance of the whole machine.